不锈钢为什么不生锈，铬起了什么作用？
Why doesn't stainless steel rust, and what does chromium do?
不锈钢含铬，表面生成极薄且致密的氧化铬钝化膜，把金属与空气、水隔开，所以耐腐蚀。
Chromium forms a thin, dense chromium-oxide passive film that seals the metal from air and water, giving corrosion resistance.
难度 专业 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#不锈钢 #铬 #钝化
为什么海边或撒了融雪盐的铁更容易生锈？
Why does iron rust faster near the sea or on salted roads?
铁生锈本就是电化学过程：水膜上铁溶成亚铁离子放出电子，氧气在另一头收电子，两边靠离子导电连成回路。纯水几乎不导电，盐溶进水膜送来大量离子，回路电阻骤降，无数微小原电池同时开动；氯离子还破坏表面氧化膜、与铁离子结成可溶物，让阳极不肯钝化。盐不是被吃掉的反应物，干燥的盐也不生锈，缺的是那层水膜；而铁锈疏松保水，不像铝的氧化膜能自阻后续腐蚀。
Rusting is already an electrochemical process: in a water film iron dissolves to ferrous ions and gives up electrons, oxygen takes electrons somewhere else in that film, and the two halves are closed by ion conduction. Pure water barely conducts, but dissolved salt floods the film with ions, so the circuit resistance collapses and countless microscopic galvanic cells run at once; chloride also breaks the surface oxide and forms soluble complexes with iron, keeping the anode from passivating. Salt is not a reactant being eaten up, and dry salt does not rust, what is missing is the water film; and rust is porous and holds water, so unlike aluminum's oxide it never shuts the attack down.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#生锈 #盐 #电化学
缝隙腐蚀是一种“浓差电池”吗？
Is crevice corrosion a concentration cell?
可以说它是，但只说对一半。缝隙太窄时溶液几乎不动，氧被消耗又补不回来，缝内贫氧、缝外富氧，便成氧浓差电池：缝内作阳极溶解，缝外作阴极。加速来自自催化：金属离子在缝内堆积、水解释出氢离子，氯离子迁入平衡电荷，酸化的静止液体又让钝化膜补不回来。边界有两条：浓差不限于氧，金属离子或氢离子的浓度差同样能成电池，无氧也一样；它与点蚀机理相近，只是被几何缝隙圈在里头。
Partly yes, but that is only half of it. In a tight crevice the solution barely moves, so oxygen is consumed faster than it can be replaced: the inside turns oxygen-poor and the outside stays oxygen-rich, forming an oxygen concentration cell in which the interior is the anode that dissolves and the exterior the cathode. The acceleration comes from autocatalysis: metal ions pile up inside, their hydrolysis releases hydrogen ions, chloride migrates in to balance the charge, and this stagnant acid solution stops the passive layer from repairing itself. Two limits worth adding: the concentration difference need not be oxygen, since differences in metal-ion or hydrogen-ion concentration make a concentration cell just as well, even without oxygen; and the mechanism is close to pitting, the difference being that geometry confines it inside a crevice.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#缝隙腐蚀 #浓差电池 #局部腐蚀
钛为什么又轻又耐腐蚀？
Why is titanium both light and corrosion-resistant?
钛密度只有钢的一半多，表面极易生成致密氧化膜(TiO2)自我钝化，所以强度高又耐蚀，广泛用于航空和植入物。
Titanium’s density is just over half of steel’s, and it self-passivates with a dense TiO2 film—strong yet corrosion-resistant, ideal for aerospace and implants.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#钛 #钝化 #轻合金
氯离子为何能在不锈钢表面诱发点蚀？试从钝化膜局部破坏与蚀孔内化学两方面说明。
How do chloride ions trigger pitting corrosion on stainless steel? Explain in terms of localized breakdown of the passive film and the chemistry inside the pit.
不锈钢依靠表面富铬氧化物钝化膜防护。氯离子半径小、侵蚀性强，优先吸附在硫化物夹杂等膜缺陷处并局部穿透，使钝化膜破裂成核为蚀孔。孔内溶解的金属离子发生水解产生氢离子，溶液酸化；氯离子迁入孔内以维持电中性，形成高浓度强腐蚀性的孔内溶液。孔外大片钝化表面充当阴极，构成大阴极-小阳极的自催化电池，驱动点蚀持续向深处发展。
Stainless steel is protected by a chromium-rich oxide passive film. Being small and highly aggressive, chloride ions preferentially adsorb at film defects such as sulfide inclusions and penetrate locally, nucleating pits where the film breaks down. Inside an occluded pit, dissolved metal cations hydrolyze, releasing protons and acidifying the solution, while chloride migrates inward to maintain electroneutrality, building a concentrated, highly corrosive electrolyte. The large passivated exterior acts as the cathode, forming a big-cathode/small-anode autocatalytic cell that drives pit growth ever deeper.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Mars G. Fontana《Corrosion Engineering》第3版, McGraw-Hill, 1986
Mars G. Fontana, Corrosion Engineering, 3rd ed., McGraw-Hill, 1986
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-07-100360-5 (1986, McGraw-Hill)
#点蚀 #钝化膜 #氯离子 #自催化腐蚀
为什么电镀能防锈？
Why does electroplating prevent rust?
用电解把一层不活泼金属镀在表面，隔绝空气和水。
Electrolysis coats a surface with inert metal, blocking air and water.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#电镀 #防腐 #涂层
混凝土里的钢筋为什么会生锈，还会把混凝土撑裂？
Why does rebar inside concrete rust and even crack it?
若保护层有裂缝或氯离子渗入，钢筋发生电化学腐蚀，铁锈体积比铁大几倍，膨胀就把混凝土胀裂。
Through cracks or chloride ingress, rebar corrodes electrochemically; rust has several times iron's volume and the expansion cracks the concrete.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#钢筋 #腐蚀 #混凝土
铜屋顶和铜像为什么会变成绿色？
Why do copper roofs and statues turn green?
铜先氧化成红棕色的氧化亚铜，再与空气中的水和二氧化碳反应生成绿色的碱式碳酸铜（铜绿）。
Copper first forms reddish cuprous oxide, then reacts with water and CO2 to form green basic copper carbonate (patina).
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#铜 #铜绿 #氧化
为什么铜和铁接在一起时铁锈得更快？
Why does iron rust faster when joined to copper?
两者形成原电池，较活泼的铁作阳极被氧化溶解，铜作阴极反而加速铁的腐蚀。
They form a galvanic cell where more active iron acts as the anode and dissolves, while copper as cathode accelerates iron corrosion.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#电偶腐蚀 #原电池 #阳极
为什么固定在船体钢板上的锌块能保护整艘船不被海水腐蚀？
Why can zinc blocks fixed to a ship's steel hull protect the whole vessel from seawater corrosion?
锌的标准电极电位比铁更负。当两者在海水中接触时便构成原电池：锌作为阳极优先氧化溶解，向钢板持续输出电子，把铁的电位负移到免蚀区，使铁只发生阴极的吸氧反应而不再失去电子溶解。腐蚀集中在锌上，锌块逐渐消耗，需要定期更换，因此称为牺牲阳极的阴极保护，广泛用于船体、码头钢桩和储罐底部。
Zinc has a more negative standard electrode potential than iron. When the two metals touch in conductive seawater they form a galvanic cell: zinc dissolves preferentially as the anode, delivering a continuous stream of electrons to the hull and polarizing the iron below its corrosion potential, so iron only sustains cathodic oxygen reduction instead of losing electrons and dissolving. Since the corrosion concentrates in the zinc, the anodes are consumed and periodically replaced; this is called sacrificial-anode cathodic protection and is widely applied to hulls, steel piles and tank bottoms.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
《腐蚀工程》，M. G. Fontana 著，第3版，McGraw-Hill，1986年
Corrosion Engineering, M. G. Fontana, 3rd ed., McGraw-Hill, 1986
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-07-100360-5 (1986, McGraw-Hill)
#牺牲阳极 #阴极保护 #电偶腐蚀
铝为什么不容易像铁那样生锈？
Why doesn't aluminum rust like iron?
铝表面会立刻形成一层致密、牢固的氧化铝保护膜，阻止内部继续被腐蚀。
Aluminum instantly forms a tight, adherent oxide layer that shields the metal beneath from further corrosion.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#铝 #氧化膜 #耐腐蚀
牺牲阳极保护法怎么防锈？
How does sacrificial-anode protection stop rust?
连接更活泼的金属（如镁、锌）作阳极先被腐蚀，从而保护船体、管道等被保护体。
A more active metal (e.g., Mg, Zn) is attached as the anode and corrodes first, protecting hulls and pipes.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#牺牲阳极 #阴极保护 #防腐
铝为什么不继续被空气腐蚀烂掉？
Why doesn't aluminum keep corroding in air?
表面瞬间生成致密的 Al₂O₃ 膜而钝化，阻隔内部金属与氧、水接触。
A dense Al₂O₃ film forms instantly and passivates the surface, blocking inner metal from oxygen and water.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#钝化 #氧化铝 #氧化膜
爸爸的自行车链条为什么会生锈变红?
Why did Dads bike chain turn rusty red?
铁遇到空气里的氧气和雨水,就会慢慢变成红褐色的锈,像生了小病。所以下雨后要给链条擦油,油像雨衣一样把水和氧气隔开。铜生绿锈,铁生红锈,金属生病颜色还不一样呢。
Iron meets rain and airs oxygen and slowly turns rusty red like catching a cold. Wipe chains with oil after rain — oil works like a raincoat keeping water and oxygen away. Copper grows green rust; iron grows red. Each metal sickens its own color.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《十万个为什么》第六版化学分册,少年儿童出版社,2013
Ten Thousand Whys: Chemistry volume, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#生锈 #防锈 #金属
铁钉放在潮湿的地方为什么会「长」红锈?
Why do iron nails grow red rust in damp places?
铁遇到水和空气里的氧气,慢慢变成一种新的物质——氧化铁,就是红棕色的锈,像铁的感冒一样一点点扩散。干燥的铁不生锈,泡在纯水里的也慢,又湿又有空气才严重。刷油漆就是给铁穿雨衣隔绝水和氧。
Iron meeting water plus oxygen slowly turns into something new — iron oxide, reddish-brown rust spreading like a cold. Dry iron never rusts; plain water is slow; damp air is worst. Painting iron gives it a raincoat blocking water and oxygen.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《十万个为什么》第六版化学分册,少年儿童出版社,2013
Ten Thousand Whys: Chemistry volume, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#生锈 #氧化 #防锈
银首饰为什么会变黑？
Why does silver jewelry turn black?
银和空气中的硫化物反应生成黑色的硫化银，这就是常见的银锈。
Silver reacts with sulfur compounds in air to form black silver sulfide, the common tarnish.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#银 #硫化 #氧化